Lamination is commonly defined as a process of applying, in a relatively permanent manner, a thin film or sheet of material to an underlying substrate. Lamination has been used in single or multiple applications to either provide a surface finish different from the underlying substrate, or to provide additional protection to the underlying substrate, or to enhance certain properties of the underlying substrate. Examples of laminated products include snow and water skis, furniture, airplane interiors, etc. Historically, such processes have involved applications to substantially smooth surfaces, at the time of lamination. Vacuum press application and other laminating processes used for laminating to a substrate with a detailed, textured or embossed surface, which surface has multiple surface plane deviations, of differing heights and depths, suffer limitations particularly on a continuous manufacturing basis. While some technological advancements have been made in batch process lamination for finished pieces with textured surfaces, the process is very labor and time intensive, with resultant higher costs and lower output. There are significant cost advantages for a process that can provide the desired finish textured product in a continuous manufacturing process, but such processes have heretofore been unavailable.
Continuous laminating processes have used conforming pressures exerted by various types of rollers, to seal the laminate against the substrate. However, such processes are most suitable for use with substrates that are substantially smooth, flat or plane surfaces, and to some extent curved and angled surfaces. In the case of a solid roller system, a uniform or near uniform conforming pressure must be continuously exerted by the rollers (or set of rollers) in order to properly bond the film to the substrate. However, solid roller technology, while a continuous process, has the limitation of being incapable of the substantial pressure needed to force the film on and into a rough or textured substrate surface and of being inapplicable where the film or substrate will not tolerate the substantial pressure needed. Also, if the substrate has an embossed or textured surface, a solid roller may fail to adequately reflect or telegraph all details of the surface. Solid rollers are also incapable of providing differential pressures on a textured surface, and so can cause undue pressure to be exerted at high points of the substrate (damaging or compromising the adhesive film and/or substrate), and insufficient pressure in the low points (causing incomplete bonding of the film to the substrate). Thus, lamination with rollers typically results in uneven pressure distribution and uneven adhesion. Vacuum/bladder technology can be used to perform lamination of uneven surfaces, however, the technology can only be performed in a batch process, resulting in the low throughput and high costs, and, therefore, is limited to end products with a relatively high intrinsic value.
While laminating procedures may exist to apply film to flat, contoured and slightly uneven surfaced substrates, there has been no suggestion of previously known technology which provides the attributes and benefits of the current invention including the ability to laminate films or sheet to embossed or textured surfaces in a continuous process using pressurized liquid, with fine telegraphing of the surface.
The potential commercial value is enormous for a process that manufactures a laminated textured product in a continuous process. The current invention provides such a process and addresses the previously noted shortcomings or inadequacies in present laminating processes and technology.